I have two newish Mac Minis, and have been having problems with both. I may have found a fix for the Mac Mini used at home as my media server.
The problem is that it regularly grey screens and has to be rebooted. It will be working away quite happily, and then the screen goes a nice shade of grey, and nothing else happens. I have to hold the power button down until the Mac Mini turns off, then bring it up and use Disk Utility on all the hard disks.
When I added the Drobo, it would repeatedly grey screen after rsyncs to the Drobo. I decided to run more tests. My second Mac Mini is a Mac Mini Server I keep at work in the vain hope of doing some iOS programming. It doesn't grey screen. I thought that I could use it at home to bring some stability to the media server, and so I can get some use out of the Drobo.
I brought the Mac Mini Server home, and I plugged it all in, and hey presto, it started grey screening. That Mac Mini hasn't done that before. So that indicated that there was something specific to home that causes Mac Minis to grey screen. What I had been suspecting for a while is my USB hard drive arrangement.
The Mac Minis have four USB ports at back. I have keyboard, mouse, and Drobo in the first three, and a powered USB hub in the last slot with the other four external hard disks plugged into the USB hub. Only problem is that the USB hub is about 8 years old. I've been reading that they sometimes die and give problems, or the older USB cables die and give problems.
I bought a Belkin 7-port powered USB hub. Only USB 2, but that will do for now. It is tiny. I was quite shocked at how small it is.
Last night, I shut down the Mac Mini Server and pulled it out. I took the Mac Mini and decided to muddy the waters and confuse the testing process and I put the 16 gig of RAM back in it. I had bought this from Crucial last year, installed it, and then removed it when the Mac Mini started grey screening. So I put the 16 gig RAM back in, plugged keyboard and mouse and Drobo in back of the Mac Mini, and plugged the new USB hub in and connected the four external HDDs to the hub. That started fine, and I let it sit for a while. No grey screen.
So I did some backups via rsync to the Drobo. I would have expected at least one grey screen incident by this time, but there was none. I continued to work the Mac Mini during the evening, and started again this morning. I have not experienced any grey screen incidents so far. I am hopeful that this may have fixed the problem. I think I will also replace the mouse. The keyboard is an Apple keyboard, so should be okay.
So the home media server might be more stable now. On the other hand, I took the Mac Mini Server back to work and plugged it in, and now about every hour, the screen goes pixellated and shimmers and then it reboots. I may need to shake it and run more tests here.
I am not having much luck with these setups.